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Evidence for recombination between a sialidase (nanH) of Actinomyces naeslundii and Actinomyces oris, previously named 'Actinomyces naeslundii genospecies 1 and 2'.

Do T, Henssge U, Gilbert SC, Clark D, Beighton D - FEMS Microbiol. Lett. (2008)

Bottom Line: However, for A. oris significant negative values in tests for neutral selection suggested the rate of mutation in A. oris was greater than in A. naeslundii but with selection against nonsynonymous mutations.This was supported by the observation that the frequency of polymorphic sites in A. oris, which were monomorphic in A. naeslundii was significantly greater than the frequency of polymorphic sites in A. naeslundii which were monomorphic in A. oris (chi(2)=7.011; P=0.00081).The higher proportions of A. oris in the oral biofilm might be explained by the higher mutation rate facilitating an increased ability to respond successfully to environmental stress.

View Article: PubMed Central - PubMed

Affiliation: King's College, School of Medicine and Dentistry, London, UK.

ABSTRACT
Actinomyces spp., predominant members of human oral biofilms, may use extracellular sialidase to promote adhesion, deglycosylate immunoglobulins and liberation of nutrients. Partial nanH gene sequences (1,077 bp) from Actinomyces oris (n=74), Actinomyces naeslundii (n=30), Actinomyces viscosus (n=1) and Actinomyces johnsonii (n=2) which included the active-site region and the bacterial neuraminidase repeats (BNRs) were compared. The sequences were aligned and each species formed a distinct cluster with five isolates having intermediate positions. These five isolates (two A. oris and three A. naeslundii) exhibited interspecies recombination. The nonsynonymous/synonymous ratio was <1 for both A. oris and A. naeslundii indicating that nanH in both species is under stabilizing selective pressure; nonsynonymous mutations are not selected. However, for A. oris significant negative values in tests for neutral selection suggested the rate of mutation in A. oris was greater than in A. naeslundii but with selection against nonsynonymous mutations. This was supported by the observation that the frequency of polymorphic sites in A. oris, which were monomorphic in A. naeslundii was significantly greater than the frequency of polymorphic sites in A. naeslundii which were monomorphic in A. oris (chi(2)=7.011; P=0.00081). The higher proportions of A. oris in the oral biofilm might be explained by the higher mutation rate facilitating an increased ability to respond successfully to environmental stress.

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Reverse transcriptase (RT)-PCR assays showing expression of nanH and the housekeeping gene atpA in the type strains of Actinomyces oris (CCUG 34288; EU805602), and Actinomyces johnsonii (CCUG 34287; EU805600), Actinomyces naeslundii (CCUG 2238; EU805601) and Actinomyces viscosus (NCTC 10951; EU805603). Negative controls, omitting the RT in the reaction mix, yielded no amplicons from any strain.
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fig03: Reverse transcriptase (RT)-PCR assays showing expression of nanH and the housekeeping gene atpA in the type strains of Actinomyces oris (CCUG 34288; EU805602), and Actinomyces johnsonii (CCUG 34287; EU805600), Actinomyces naeslundii (CCUG 2238; EU805601) and Actinomyces viscosus (NCTC 10951; EU805603). Negative controls, omitting the RT in the reaction mix, yielded no amplicons from any strain.

Mentions: The type strains of each of the four species examined expressed the nanH gene when grown on a complex medium containing defibrinated horse blood and 1% (w/v) glucose (Fig. 3) and sequence analysis confirmed that the individual products were derived from the nanH genes of the appropriate species.


Evidence for recombination between a sialidase (nanH) of Actinomyces naeslundii and Actinomyces oris, previously named 'Actinomyces naeslundii genospecies 1 and 2'.

Do T, Henssge U, Gilbert SC, Clark D, Beighton D - FEMS Microbiol. Lett. (2008)

Reverse transcriptase (RT)-PCR assays showing expression of nanH and the housekeeping gene atpA in the type strains of Actinomyces oris (CCUG 34288; EU805602), and Actinomyces johnsonii (CCUG 34287; EU805600), Actinomyces naeslundii (CCUG 2238; EU805601) and Actinomyces viscosus (NCTC 10951; EU805603). Negative controls, omitting the RT in the reaction mix, yielded no amplicons from any strain.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2667307&req=5

fig03: Reverse transcriptase (RT)-PCR assays showing expression of nanH and the housekeeping gene atpA in the type strains of Actinomyces oris (CCUG 34288; EU805602), and Actinomyces johnsonii (CCUG 34287; EU805600), Actinomyces naeslundii (CCUG 2238; EU805601) and Actinomyces viscosus (NCTC 10951; EU805603). Negative controls, omitting the RT in the reaction mix, yielded no amplicons from any strain.
Mentions: The type strains of each of the four species examined expressed the nanH gene when grown on a complex medium containing defibrinated horse blood and 1% (w/v) glucose (Fig. 3) and sequence analysis confirmed that the individual products were derived from the nanH genes of the appropriate species.

Bottom Line: However, for A. oris significant negative values in tests for neutral selection suggested the rate of mutation in A. oris was greater than in A. naeslundii but with selection against nonsynonymous mutations.This was supported by the observation that the frequency of polymorphic sites in A. oris, which were monomorphic in A. naeslundii was significantly greater than the frequency of polymorphic sites in A. naeslundii which were monomorphic in A. oris (chi(2)=7.011; P=0.00081).The higher proportions of A. oris in the oral biofilm might be explained by the higher mutation rate facilitating an increased ability to respond successfully to environmental stress.

View Article: PubMed Central - PubMed

Affiliation: King's College, School of Medicine and Dentistry, London, UK.

ABSTRACT
Actinomyces spp., predominant members of human oral biofilms, may use extracellular sialidase to promote adhesion, deglycosylate immunoglobulins and liberation of nutrients. Partial nanH gene sequences (1,077 bp) from Actinomyces oris (n=74), Actinomyces naeslundii (n=30), Actinomyces viscosus (n=1) and Actinomyces johnsonii (n=2) which included the active-site region and the bacterial neuraminidase repeats (BNRs) were compared. The sequences were aligned and each species formed a distinct cluster with five isolates having intermediate positions. These five isolates (two A. oris and three A. naeslundii) exhibited interspecies recombination. The nonsynonymous/synonymous ratio was <1 for both A. oris and A. naeslundii indicating that nanH in both species is under stabilizing selective pressure; nonsynonymous mutations are not selected. However, for A. oris significant negative values in tests for neutral selection suggested the rate of mutation in A. oris was greater than in A. naeslundii but with selection against nonsynonymous mutations. This was supported by the observation that the frequency of polymorphic sites in A. oris, which were monomorphic in A. naeslundii was significantly greater than the frequency of polymorphic sites in A. naeslundii which were monomorphic in A. oris (chi(2)=7.011; P=0.00081). The higher proportions of A. oris in the oral biofilm might be explained by the higher mutation rate facilitating an increased ability to respond successfully to environmental stress.

Show MeSH
Related in: MedlinePlus